The present invention relates to a system and method for servicing communications between a base station and plural mobile stations in mobile communications such as automobile radio communications.
In a conventional mobile communication system, frequency division multiple access (abbreviated to FDMA) has been used (refer to JP-A-114498/1988). According to that method, a base station branch-outputs a receive carrier signal from a current data collecting mobile station to the next mobile station according to one-to-N polling system. Mobile stations specified by the base station for data collection mutually and sequentially monitor the carrier signal and then start to transmit data to the base station when the off-state of the carrier signal is detected.
A method of adding retransmission request information when transmission data in a base station exceeds a specified length and then requesting the remaining data transmission by means of the base station after a completion of polling operation has been used as a polling control method in a mobile communication system (refer to JP-A-276935/1989).
On the other hand, a communication system is known that uses time division multiplex access (hereinafter, often referred to as TDMA) to transmit data from a base station to mobile stations (hereinafter, often referred to as down-stream), and time division multiple access to transmit data from a mobile station to the base station (hereinafter often referred to as up-stream).
However, one communication channel corresponds to one mobile station in the conventional communication method. Hence, there has been the disadvantage that the number of stations per communication channel cannot be increased, so that the transmission efficiency cannot be improved.